1. Field of the Invention
The present invention relates to a liquid discharge apparatus and a liquid discharge method based on the use of the same.
2. Description of the Related Art
An ink-jet head is known as a liquid discharge apparatus, the ink-jet head comprising a channel unit which is formed with ink channels including a plurality of nozzles, and a piezoelectric actuator which discharges ink from the plurality of nozzles respectively. The channel unit has a plurality of pressure chambers which are communicated with the plurality of nozzles respectively. The piezoelectric actuator is joined to the channel unit so that the plurality of pressure chambers are covered therewith.
The piezoelectric actuator has a piezoelectric layer, a plurality of individual electrodes, and a common electrode. The plurality of individual electrodes are provided while corresponding to the plurality of pressure chambers respectively on a surface of the piezoelectric layer disposed on the side opposite to the channel unit. The common electrode is arranged so that the common electrode is commonly opposed to the plurality of individual electrodes with the piezoelectric layer intervening therebetween, on a surface of the piezoelectric layer disposed on the side of the channel unit. The plurality of individual electrodes are connected to a driver IC for driving the piezoelectric actuator via a wiring member. Further, the common electrode is always retained at the ground electric potential.
The driver IC outputs the driving signal to the individual electrode corresponding to the nozzle from which the ink is to be discharged so that the electric potential of the individual electrode is switched between the driving electric potential and the ground electric potential. Accordingly, the voltage, which is applied to the portion of the piezoelectric layer interposed between the individual electrode and the common electrode (hereinafter referred to as “piezoelectric element” as well), is changed. In this situation, the contraction occurs in the piezoelectric element, and the piezoelectric actuator is deformed so that the piezoelectric actuator is warped or bent. Accordingly, the volume of the pressure chamber is changed, and the discharge energy is applied to the ink contained in the pressure chamber.